Mowers are particularly useful for cutting grass, for clearing brush, for maintaining fields, and for performing many other landscaping functions. Because tractors can operate in virtually any terrain, it is desirable to attach a mower to a tractor. Brush-cutting mowers are used extensively to clear vegetation from large tracts of land. Large single blade brush-cutting mowers are well known in the art, and are typically integrally attached to the rear end of a specially manufactured tractor.
In one particular application, brush-cutting mowers are used to cut vegetation growing in powerline right-of-ways. The vegetation in a powerline right-of-way must be periodically cut to maintain access to the powerlines and to minimize energy losses from the powerlines. Access is required to facilitate service and repair of the powerlines. Excessive energy losses may occur when high, dense vegetation beneath the powerlines draw electricity out of the overhead powerlines. In another application, brush-cutting mowers are periodically used to cut the vegetation that grows in medians and along roadways. Cutting the vegetation in those areas improves visibility and provides a shoulder along the road for emergency stops and for pedestrian and bicycle traffic. Another application is on pipeline rights-of-way above pipelines, where vegetation may interfere with pipeline walkovers and aerial inspections. The ability to cut, and simultaneously apply treatment fluids to the root system of vegetation, to kill or reduce the growth of vegetation within powerline rights-of-way, is highly beneficial for reducing costs of pipeline inspections.
Existing brush-cutting mowers either have a relatively expensive single blade that approximates the width of the tractor to which it is attached or have a relatively inexpensive single blade that is considerably narrower than the width of the tractor to which it is attached. Neither of those options provide an adequate means for clearing vegetation from a parcel of land.
A longer blade results in an increased cut path and thereby reduces the number of passes the tractor operator needs to make to clear vegetation from a parcel of land. However, blades this large are very heavy and very difficult to manufacture. The size of the blade makes repair and maintenance of the brush-cutting mower expensive and time consuming. Because of the heavy weight of the blade, more than one person is required to remove the blade from the mower. Consequently, either more workmen must be provided at every job site or the operator must wait for help to arrive before necessary repairs can be made. This leads to a significant increase in the cost of operating existing brush-cutting mowers.
Large blades are also exponentially more expensive to manufacture. Consequently, the blade is a relatively expensive component of the brush-cutting mower.
The considerable weight of a large blade also necessitates a significant amount of power to operate the blade. Consequently, relatively heavy and expensive power sources are needed to provide sufficient power to operate the blade. Power sources of this magnitude are exponentially more expensive than smaller power sources. Thus, it is desirable for the blade to be as light as possible to reduce the mower's power requirements while not affecting its ability and durability when cutting from three inch to six inch basal diameter trees.
Using a brush-cutting mower that has a smaller blade and thus a narrower cut path are equally inefficient. When the cut path is narrower than the width of the tractor the mower is attached to, the mower operator must make overlapping passes when clearing vegetation from a parcel of land. While there are considerable savings from operating a smaller blade, these gains are off-set by the increases in the time and cost required to clear the parcel of land.
A need, therefore, exists for a relatively inexpensive brush-cutting mower that can cut a path at least as wide as the tractor to which it is attached, and that can apply treatment fluid to the cut brush and vegetation, preferably in one pass over the cutting path.
Another drawback of existing single blade brush-cutting mowers is the lack of consistent blade exposure. Typically, the housing of an existing brush-cutting mower includes a deck having a clam shell portion. When the brush-cutting mower is not in operation, the deck completely covers the blade. When the brush-cutting mower is in operation, the clam shell portion of the deck is moved away from the blade, and a portion of the blade is exposed. The configuration of the clam shell portion and the circular path of the blade prevent uniform blade exposure for brush to be cut off-center of the forward or rearward path of the axis of the blade. Consequently, existing single blade brush-cutting mowers can be cumbersome to operate and may require multiple passes to obtain equivalent cut-height for a cleared pathway through brush.
Another problem with existing brush-cutting mowers is that the mowers are mounted to the rear end of the tractor. Consequently, the tractor contacts the vegetation prior to the blades on the mower. The weight and force of the tractor typically bends or compresses the vegetation down. As a result, the blade will be unable to cut many of the stems of the vegetation. Therefore, the bent and uncut vegetation will not be cut by the blade as the mower itself passes over the already bent over stem.
Furthermore, because the mower operator faces forward, he has less control over the path of the mower blade. Finally, when the tractor turns the rear mounted mower does not take the same path as the tractor. Numerous problems arise when the tractor path does not correspond to the path of the blade.
Because the tractor encounters the vegetation before the blades can cut the vegetation, the tractor must have sufficient power to run over the vegetation, and to drag a mower blade housing over the brush. Thus, in areas where the brush is particularly thick, the power requirements of the tractor may increase dramatically. Because of the density of the brush is typically unknown in a given job, most existing mowers use large expensive tractors having large horsepower capabilities to perform even the simplest jobs.
In addition, existing mowers may have herbicide spraying capabilities added to the front or rear of the mower, or associated with the mowing blades, but existing blade and spray configurations allow for indiscriminate spraying of treatment liquids onto the outer surfaces of vegetation and onto the ground, requiring spray applications of 20 gallons/acre or more of vegetation sprayed while contributing to "run-off" of excess fluids into streams and lakes.
While turf mowers having multiple blades are known, there are no known brush-cutting mowers that utilize small multiple blades that are belt driven and that have a similar configuration as the present invention, allowing simultaneous application of treatment fluid during cutting of brush and vegetation.